// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "base/win/wrapped_window_proc.h"

#include "base/atomicops.h"
#include "base/logging.h"

namespace {

base::win::WinProcExceptionFilter s_exception_filter = NULL;

HMODULE GetModuleFromWndProc(WNDPROC window_proc)
{
    HMODULE instance = NULL;
    // Converting a pointer-to-function to a void* is undefined behavior, but
    // Windows (and POSIX) APIs require it to work.
    void* address = reinterpret_cast<void*>(window_proc);
    if (!::GetModuleHandleExA(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS | GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
            static_cast<char*>(address),
            &instance)) {
        NOTREACHED();
    }
    return instance;
}

} // namespace.

namespace base {
namespace win {

    WinProcExceptionFilter SetWinProcExceptionFilter(
        WinProcExceptionFilter filter)
    {
        subtle::AtomicWord rv = subtle::NoBarrier_AtomicExchange(
            reinterpret_cast<subtle::AtomicWord*>(&s_exception_filter),
            reinterpret_cast<subtle::AtomicWord>(filter));
        return reinterpret_cast<WinProcExceptionFilter>(rv);
    }

    int CallExceptionFilter(EXCEPTION_POINTERS* info)
    {
        return s_exception_filter ? s_exception_filter(info) : EXCEPTION_CONTINUE_SEARCH;
    }

    BASE_EXPORT void InitializeWindowClass(
        const char16* class_name,
        WNDPROC window_proc,
        UINT style,
        int class_extra,
        int window_extra,
        HCURSOR cursor,
        HBRUSH background,
        const char16* menu_name,
        HICON large_icon,
        HICON small_icon,
        WNDCLASSEX* class_out)
    {
        class_out->cbSize = sizeof(WNDCLASSEX);
        class_out->style = style;
        class_out->lpfnWndProc = window_proc;
        class_out->cbClsExtra = class_extra;
        class_out->cbWndExtra = window_extra;
        // RegisterClassEx uses a handle of the module containing the window procedure
        // to distinguish identically named classes registered in different modules.
        class_out->hInstance = GetModuleFromWndProc(window_proc);
        class_out->hIcon = large_icon;
        class_out->hCursor = cursor;
        class_out->hbrBackground = background;
        class_out->lpszMenuName = menu_name;
        class_out->lpszClassName = class_name;
        class_out->hIconSm = small_icon;

        // Check if |window_proc| is valid.
        DCHECK(class_out->hInstance != NULL);
    }

} // namespace win
} // namespace base
